Various fragmentable warhead casings have been designed in the past. For example, U.S. Pat. No. 358,627 to G. F. Simonds discloses a roll formed projectile. The projectile in being roll formed is made up of bar stock. U.S. Pat. No. 3,566,794 to J. Pearson et al. relates to an explosive fragmentable warhead casing. The casing is of double-wall construction such that the interior annular surface of each wall is provided with an intersecting series of helical grooves to form a diamond-shaped groove pattern. Since the double walls are rotatable relative to each other about the casing axis, the groove pattern of each wall is adjusted relative to the other groove pattern so as to control the shape and mass of the fragments produced by the casing when subjected to impulsive loading during casing use. U.S. Pat. No. 4,068,590 to J. Pearson relates to an explosive warhead casing of single wall construction. The interior annular surface of the casing is provided with a diamond-shaped groove pattern. The cross-sectional shape of each groove of the pattern is of nonsymmetrical configuration. Consequently, by reason of the cross-sectional shape of each groove, the particular shape and mass of each fragment produced by the casing when subject to impulsive loading is reasonably predictable. U.S. Pat. No. 4,312,274 to L. Zernow concerns an explosive warhead casing of liner/casing construction. The casing is provided with an interior annular surface having a diamond-shaped groove pattern. Similarly, the exterior surface of the liner is also provided with a confronting diamond-shaped groove pattern. Inasmuch as the casing and liner are movable relative to each other about the casing axis and inasmuch as the groove pattern of the liner can be filled with a fluid, the shape and size of the fragments produced by the casing are selectively controllable depending on whether the target to be impacted by a weapon incorporating the casing is considered hard or soft.
The aforementioned references failed to recognize that a fragmentable warhead with greater fragmentation control is achievable if the casing (from which a plurality of fragments are produced) is initially not a one-piece sleeve as was the practice in the past. In other words, if the warhead fragmentable casing is initially made up of a plurality of metallurgically bonded, interconnected and selectively arranged elements about the warhead axis. To this end, each casing is preferably initially formed from a plurality of stacked rings or from a progressively mandrel wound endless length of rod or wire. Then the adjacent peripheral contacting surfaces of adjoining circumferential portions are precisely laser welded together so as to form a unique unitized fragmentable casing design. By reason of this design, a casing can be formed not only with minimal machining requirements, but also with greater selection as to diameter, thickness, mass and material used so as to be able to form fragments with greater control as to mass, shape and size in meeting weapon and target requirements. Perhaps one of the reasons the prior art failed to recognize the usefulness in forming a unitized casing of metallurgically bonded and interconnected elements is that the advantages of laser technology had not yet been fully realized in relation to warhead casing manufacture.
However, none of the aforediscussed references, whether taken alone or in any combination, remotely suggest the improved explosive warhead casing of single wall construction and enhanced fragmentation design. The casing is generally made up of a plurality of stacked ring-like means. Adjacent outer peripheral portions of adjoining ring-like means of the plurality are metallurgically bonded together so as to form a casing of unitized construction between its ends. A series of relatively spaced and longitudinally extending grooves are formed on and about the interior annular surface of the casing. By reason of the interfacial contact between adjoining ring-like means at the interior of the casing together with the first series of grooves, the casing is provided with an internal grid pattern. A second series of relatively spaced and longitudinally extending grooves are preferably formed on and about the external annular surface of the casing. Because of the second series of grooves together with the bond between adjoining ring-like means, the casing is provided in effect with an external grid pattern. By reason of these patterns, the fragments produced by the casing when subject to impulsive loading of an explosion are of a more predictable shape and mass than heretofore possible thereby resulting in each produced fragment more closely approximating the intended shape and mass of a designed fragment. Consequently, the improved casing can be tailored with precision to meet a wider range of fragment shape and mass in meeting both target and weapon requirements.